Enhanced thin film deposition

ABSTRACT

Methods of producing metal-containing thin films with low impurity contents on a substrate by atomic layer deposition (ALD) are provided. The methods preferably comprise contacting a substrate with alternating and sequential pulses of a metal source chemical, a second source chemical and a deposition enhancing agent. The deposition enhancing agent is preferably selected from the group consisting of hydrocarbons, hydrogen, hydrogen plasma, hydrogen radicals, silanes, germanium compounds, nitrogen compounds, and boron compounds. In some embodiments, the deposition-enhancing agent reacts with halide contaminants in the growing thin film, improving film properties.

REFERENCE TO RELATED APPLICATIONS

The present application claims priority as a continuation of U.S.application Ser. No. 14/812,139, filed Jul. 29, 2015, which claimspriority as a continuation of U.S. application Ser. No. 13/766,469,filed Feb. 13, 2013, now U.S. Pat. No. 9,127,351, which in turn claimspriority to U.S. application Ser. No. 11/588,837, filed Oct. 27, 2006,now U.S. Pat. No. 8,993,055, which in turn claims priority to U.S.Provisional application No. 60/730,986, filed Oct. 27, 2005. Each of thepriority applications are incorporated by reference herein.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates generally to processes for producing thinfilms with low impurity contents on a substrate by atomic layerdeposition. In some embodiments, the films produced by the atomic layerdeposition (ALD) processes disclosed herein can be used in metal gateand metal electrode applications in metal oxide semiconductor fieldeffect transistors (MOSFETs) or as barrier layers in interconnectstructures.

Description of the Related Art

Atomic layer deposition (ALD) is a self-limiting process, wherebyalternated pulses of reaction precursors saturate a substrate surfaceand leave no more than one monolayer of material per pulse. Thedeposition conditions and precursors are selected to ensureself-saturating reactions, such that an adsorbed layer in one pulseleaves a surface termination that is non-reactive with the gas phasereactants of the same pulse. A subsequent pulse of different reactantsreacts with the previous termination to enable continued deposition.Thus, each cycle of alternated pulses leaves no more than about onemolecular layer of the desired material. The principles of ALD typeprocesses have been presented by T. Suntola, e.g. in the Handbook ofCrystal Growth 3, Thin Films and Epitaxy, Part B: Growth Mechanisms andDynamics, Chapter 14, Atomic Layer Epitaxy, pp. 601-663, ElsevierScience B.V. 1994, the disclosure of which is incorporated herein byreference.

In a typical ALD process for depositing thin films, one deposition cyclecomprises exposing the substrate to a first precursor, removingunreacted first reactant and reaction byproducts from the reactionchamber, exposing the substrate to a second precursor, followed by asecond removal step. Typically, halide precursors, such as TiCl₄ andHfCl₄, are used as precursors in ALD deposition because those precursorsare inexpensive and relatively stable, but at the same time reactivetowards different types of surface groups. H₂O and NH₃ are widely usedfor oxide and nitride deposition, respectively, as second precursors.

ALD processes typically produce thin films that have lower impuritycontent at the same deposition temperature than chemical vapordeposition (CVD) processes. Despite the lower impurity levels in ALDfilms, the impurity content in ALD films can still be a problem. Thereare several possible reasons for the presence of impurities in thinfilms deposited by ALD. In some cases, the semiconductor process flownecessarily limits the maximum deposition temperature such that thatsome residues are left in the film. ALD films deposited from chloride orother halide-containing precursors (e.g., WF₆) at relatively lowtemperatures can comprise relatively high levels of halide residues.Halide impurities are present mainly at the interfaces, which can alsolead to problems. In some cases, like low temperature deposition oftransition metal nitrides and transition metal carbides from halidecontaining precursors the, impurity contents can be above the acceptablelimit for some integrated circuit (IC) applications. In another example,in some applications amorphous films are needed, which limits the growthtemperature.

Another disadvantage of the residues remaining in the film as it isdeposited is that they may block the growth and result in a lower growthrate. For example, a high growth temperature may be chosen because thefilms are impure at low temperatures. However, the number of reactiveactive sites, such as —OH or —NH_(x) groups, is higher at lowtemperatures As a result, the growth rate is substantially lowered byimpurities.

U.S. Patent Application No. 2004/0208994 to Harkonen et al. describes amethod for ALD deposition of carbon-containing transition metal films.As an example, Harkonen et al. deposited carbon containing titaniumfilms (example 1B) at a deposition temperature of about 500° C. usingTiCl₄ and trimethylaluminum (TMA) as precursors. The disadvantage ofthis process is that it needs a substantially high depositiontemperature in order to achieve low impurity contents, chlorine in theircase. Furthermore, it is widely known in art that TMA will decomposewhen used at such high temperatures. By decomposing TMA, the uniquenessof ALD, i.e., saturated and surface controlled reactions, which leads tosuperb conformality and uniformity of ultra-thin films over thelarge-area substrates, may be lost. If the same carbon containingtitanium film process is performed at temperatures below thedecomposition temperature of TMA, for example at 350° C., the chlorinecontent of the film will be undesirably high.

Accordingly, there is a need in the art for a low temperature ALD methodfor producing metal-containing films from halide (e.g., chlorine)containing metal precursors at low temperatures and with low halogenimpurity levels in the films.

SUMMARY OF THE INVENTION

According to some embodiments of the invention, a deposition-enhancingagent is utilized in ALD processes for depositing a metal orsilicon-containing film from a halide-containing precursor. In apreferred embodiment, the deposition-enhancing agent is selected fromthe group consisting of hydrocarbons, hydrogen, hydrogen plasma,hydrogen radicals, silanes, germanium compounds, nitrogen compounds,boron compounds and boranes. In a more preferred embodiment, thedeposition-enhancing agent is a hydrocarbon, preferably a hydrocarbonselected from the group consisting of alkanes, alkenes and alkynes. Thedeposition enhancing agent may be provided in each ALD cycle, or atintervals during the deposition process.

In one embodiment of the invention, atomic layer deposition (ALD)processes for forming a metal-carbide thin film are disclosed. Theprocesses preferably comprise contacting a substrate in a reaction spacewith alternating and sequential pulses of a metal source chemical thatcomprises at least one halide ligand, a second source chemicalcomprising a metal and carbon and a third source chemical, wherein thethird source chemical is a deposition-enhancing agent. In oneembodiment, the deposition enhancing agent is a hydrocarbon, preferablyacetylene. The second source chemical may comprise an organic ligand,and in one embodiment is preferably TMA or TEA (triethylaluminum).

In another embodiment, ALD processes for forming a metal carbide filmare disclosed, in which alternating and self-saturating pulses ofreactants are provided in a plurality of deposition cycles. Each cyclepreferably comprises contacting a substrate in a reaction space withalternating and sequential pulses of a first metal source chemical,preferably a halide compound, a second source chemical comprisingcarbon, and a third source chemical, wherein the third source chemicalis a hydrocarbon. The third source chemical is preferably selected fromthe group consisting of alkanes, alkenes and alkynes and in oneembodiment is acetylene.

In still another embodiment of the invention, atomic layer deposition(ALD) processes for forming oxygen-containing thin films on a substrateare disclosed. The processes preferably comprise contacting thesubstrate with alternating and sequential pulses of a metal reactant, asecond reactant comprising an oxygen source and a deposition-enhancingagent. The metal reactant is preferably a halide and typically comprisesa metal selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr,Mo, W and Al. The deposition enhancing agent is preferably ahydrocarbon, such as acetylene. The oxygen source may be, for example,H₂O, O₂, ozone, oxygen radicals or oxygen plasma.

In yet another embodiment of the invention, atomic layer deposition(ALD) processes for forming elemental thin films on a substrate aredisclosed. The processes preferably comprise contacting the substratewith alternating and sequential pulses of a metal a deposition-enhancingagent, a metal source chemical and a reducing agent. The reducing agentis preferably selected from the group consisting of boranes and silanes.The deposition enhancing agent may be, for example, a boron compoundsuch as triethyl boron (TEB).

In yet another embodiment of the invention, atomic layer deposition(ALD) processes for forming a silicon-containing thin film, such as ametal silicide, on a substrate are disclosed. The processes preferablycomprise contacting the substrate with alternating and sequential pulsesof a metal source chemical, a silicon source chemical and adeposition-enhancing agent. The silicon source chemical may be, forexample, a silane. In one embodiment the deposition enhancing agent is aboron compound, such as TEB.

In yet another embodiment of the invention, a semiconductor devicestructure is disclosed. The structure comprises a substrate and a thinfilm layer overlying the substrate, wherein the thin film layer isformed by atomic layer deposition (ALD) by contacting the substrate withalternating and sequential pulses of a metal source chemical, an oxygen,nitrogen, carbon, or silicon source chemical, and a deposition-enhancingagent.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood from the Detailed Description ofthe Preferred Embodiments and from the appended drawings, which aremeant to illustrate and not to limit the invention, and wherein:

FIG. 1 is a flow chart generally illustrating a method of forming abinary compound by atomic layer deposition (ALD), in which supply of adeposition-enhancing agent follows removal of excess second reactant andby-products, in accordance with preferred embodiments of the invention;

FIG. 2 is an x-ray photoelectron spectroscopy (XPS) sputtering timeprofile of a highly conductive tungsten silicide (WSi_(x)) film formedwith pulsing sequence WF₆/N₂/Si₂H₆/N₂/TEB/N₂;

FIG. 3 is a schematic cross-sectional side view of a electrodestructure, comprising a layer of a conductive metal carbide, accordingto preferred embodiments of the invention; and

FIG. 4 is a schematic cross-sectional side view of a dual damascenestructure, comprising a metal carbide thin barrier layer formed over thetrench and via, according to preferred embodiments of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention advantageously enables thin film formation atlower temperatures with reduced impurity levels by employing adeposition enhancing agent. In some preferred embodiments, thedeposition enhancing agents are hydrocarbons, more preferablyunsaturated hydrocarbons such as alkanes, alkenes and alkynes.

Definitions

In context of the present invention, “an ALD process” generally refersto a process for producing thin films over a substrate in which a thinfilm is formed molecular layer by molecular layer due to self-saturatingchemical reactions. The general principles of ALD are disclosed, e.g.,in U.S. Pat. Nos. 4,058,430 and 5,711,811, the disclosures of which areincorporated herein by reference. In an ALD process, gaseous reactants,i.e., precursors, are conducted into a reaction chamber of an ALD typereactor where they contact a substrate located in the chamber to providea surface reaction. The pressure and the temperature of the reactionchamber are adjusted to a range where physisorption (i.e. condensationof gases) and thermal decomposition of the precursors are avoided.Consequently, only up to one monolayer (i.e. an atomic layer or amolecular layer) of material is deposited at a time during each pulsingcycle. The actual growth rate of the thin film, which is typicallypresented as A/pulsing cycle, depends, for example, on the number ofavailable reactive surface sites or active sites on the surface andbulkiness of the chemisorbing molecules. Gas phase reactions betweenprecursors and any undesired reactions of by-products are inhibitedbecause precursor pulses are separated from each other by time and thereaction chamber is purged with an inactive gas (e.g. nitrogen or argon)and/or evacuated using, e.g., a pump between precursor pulses to removesurplus gaseous reactants and reaction by-products from the chamber.

“Reaction space” is used to designate a reactor or reaction chamber, oran arbitrarily defined volume therein, in which conditions can beadjusted to effect thin film growth by ALD. Typically the reaction spaceincludes surfaces subject to all reaction gas pulses from which gases orparticles can flow to the substrate, by entrained flow or diffusion,during normal operation. The reaction space can be, for example, in asingle-wafer ALD reactor or a batch ALD reactor, where deposition onmultiple substrates takes place at the same time.

“Adsorption” is used to designate a chemical attachment of atoms ormolecules on a surface.

“Surface” is used to designate a boundary between the reaction space anda feature of a substrate.

“Thin film” means a film that is grown from elements or compounds thatare transported as separate ions, atoms or molecules via vacuum, gaseousphase or liquid phase from the source to the substrate. The thickness ofthe film depends upon the application and may vary in a wide range,preferably from one atomic layer to 1,000 nm or more. In someembodiments, the thin film is less than about 20 nm in thickness, evenmore preferably less than about 10 nm and most preferably less thanabout 5 nm.

“Metallic thin film” designates a thin film that comprises metal. Ametallic thin film may be an elemental metal thin film comprisedessentially of elemental metal. Depending on the reducing agent, theelemental metal thin film may contain some metal carbide, metal nitrideand/or metal oxide in an amount that does not have a negative effect onthe characteristic metal properties of the film. In addition, a metallicthin film may be a compound metal thin film comprised essentially ofcompound metal, such as metal oxide, metal nitride, metal carbide, metalsilicon compound, or metal nitride carbide (e.g., WN_(x)C_(y)).

Subscripts “x” and “y” are used to designate species that are notnecessarily stoichiometric, having a wide range of phases with varyingmetal/oxygen, metal/carbon, metal/nitrogen, or metal/carbon/nitrogenratios.

Preferred ALD Methods

The methods presented herein allow deposition of conformal thin films onsubstrate surfaces. In preferred embodiments, thin films are depositedfrom halogen-containing chemicals. Geometrically challengingapplications are also possible due to the self-limited nature of thesurface reactions.

According to the preferred embodiments, an atomic layer deposition (ALD)type process is used to form thin films, preferably metallic thin films,on substrates, such as integrated circuit workpieces. The surfaces onwhich the thin films are deposited can take a variety of forms. Examplesinclude, but are not limited to, silicon, silicon oxide (SiO₂), coatedsilicon, dielectric materials, low-k materials, metals such as copperand aluminum, metal alloys, metal oxides and various nitrides, such astransition metal nitrides and silicon nitride or a combination of saidmaterials.

In a preferred embodiment of the invention, a substrate or workpieceplaced in a reaction chamber is subjected to alternately repeatedsurface reactions. In particular, thin films are formed by repetition ofa self-limiting ALD cycle. Preferably, each ALD cycle comprises at leastthree distinct phases. In the case of compound metallic thin filmdeposition, at least three different source chemicals are alternativelyemployed, corresponding to the three phases. One reactant will form nomore than about one monolayer on the substrate surface and includes ametal species desired in the layer being deposited. This reactant, alsoreferred to herein as “the metal reactant,” is preferably a halide, andthus the deposited monolayer is terminated with halogen ligands.

A second reactant preferably contains another species desired in thelayer being deposited, such as nitrogen, carbon, silicon and/or oxygen.However, in some embodiments, such as the deposition of elementalmetals, the second reactant does not contribute to the growing film.

The second reactant is typically not a halide, although in someembodiments it may be. In a preferred embodiment the second reactantcomprises a metal and carbon. In some embodiments, the second reactantis TMA or TEA. In other embodiments, the second reactant is water. Instill other embodiments, the second reactant is a metal-containingsource chemical comprising at least one ligand, such as a metalorganiccompound. Further, in some embodiments the second reactant can alsoleave some amount of metal in the film being deposited. For example, incase of TMA or TEA, some amount of aluminum may be left in the film,depending on the particular reaction conditions.

The third reactant is preferably a deposition-enhancing agent.Preferably the deposition-enhancing agent is capable of reducing thelevel of contaminants in the growing film. Thus, in some embodiments thethird reactant is able to remove halides from the growing film and/orfrom the reaction space. The third reactant may be a carbon compound,preferably one that is a strong reducer. Moreover, in some embodimentsthe third reactant also provides a species desired in the thin film,such as carbon, nitrogen, silicon or oxygen.

The deposition-enhancing agent is preferably selected from the groupconsisting of hydrocarbons, hydrogen, hydrogen plasma, hydrogenradicals, silanes, germanium compounds, nitrogen compounds, boroncompounds and boranes. In a more preferred embodiment, thedeposition-enhancing agent is a hydrocarbon selected from the groupconsisting of alkanes, alkenes and alkynes. In other embodiments thedeposition-enhancing agent is triethyl boron (TEB) or acetylene (C₂H₂).

The deposition enhancing agent may be provided in each ALD cycle or atintervals during the deposition process. For example, in someembodiments the deposition enhancing agent is provided every one to fourALD cycles. At the time the deposition enhancing agent is provided, thefilm grown in the most recent ALD cycles is preferably thin enough thatthe deposition enhancing agent can penetrate the film. In addition, ifthe deposition enhancing agent comprises radicals, it is preferablyprovided initially at a point in the deposition process such that it isnot able to penetrate the deposited film and damage the underlyingsubstrate material.

In one phase of the ALD cycle (“the metal phase” or the “first phase”),the reactant or source chemical comprising a metal species is suppliedto the reaction chamber and chemisorbs to the substrate surface. Thereactant supplied in this phase is selected such that, under thepreferred conditions, the amount of reactant that can be bound to thesurface is determined by the number of available binding sites and bythe physical size of the chemisorbed species (including ligands). Thechemisorbed layer left by a pulse of the metal reactant isself-terminated with a surface that is non-reactive with the remainingchemistry of that pulse. This phenomenon is referred to herein as“self-saturation.” One of skill in the art will recognize that theself-limiting nature of this phase makes the entire ALD cycleself-limiting. Excess reactant and reactant byproducts (if any) areremoved from the reaction space, for example by purging with an inertgas and/or evacuation.

Maximum step coverage on the workpiece surface is obtained when no morethan about a single molecular layer of metal source chemical moleculesis chemisorbed in each self-limiting pulse. Due to the size of thechemisorbed species and the number of reactive sites, somewhat less thana monolayer (ML) may be deposited in each pulse of metal reactant.

In the next phase of the cycle, a pulse of a second source chemical isprovided that reacts with the molecules left on the substrate surface bythe preceding pulse. In some embodiments the source chemical preferablycomprises a species that is to be incorporated in the thin film, such asnitrogen, oxygen, silicon or carbon. Thus, the desired species isincorporated into the thin film by the interaction of the sourcechemical with the monolayer left by the metal reactant. This phase isreferred to herein as “the second phase” or the “species-contributingphase.” In particular embodiments, the second source chemical is asilicon, nitrogen, oxygen or carbon containing compound and its reactionwith the chemisorbed metal species produces a metal silicide, nitride,oxide or carbide layer on the substrate. In other embodiments the secondsource chemical is a metal source chemical, such as TMA, and metal isincorporated into the growing film. In some preferred embodiments thespecies-contributing source chemical comprises metal and carbon.

In still other embodiments the second source chemical is notincorporated in the film to any appreciable extent. For example, in someembodiments the second reactant is a reducing agent that at leastpartially reduces the adsorbed first reactant to an elemental metal.

Excess second source chemical and reaction byproducts, if any, areremoved from the reaction space by purging and/or evacuation.

The third phase of the ALD cycle comprises providing adeposition-enhancing agent. In the preferred embodiments the depositionenhancing agent is capable of removing halides or other contaminants orundesired reaction byproducts from the growing thin film and/or from thereaction chamber. In addition, the deposition-enhancing agent maycomprise a species that may be incorporated into the thin film, such ascarbon, boron or silicon. This is referred to as the “third phase” orthe “deposition-enhancing phase.”

Although referred to as the “first phase,” the “second phase” and the“third phase,” these labels are for convenience and do not indicate theactual order of the phases in each ALD cycle. Thus, the initial ALDcycle may be started with any of the three phases described above.However, one of skill in the art will recognize that if the initial ALDcycle does not begin with the metal reactant phase, at least two ALDcycles will typically need to be completed to deposit about a monolayerof the desired thin film.

In addition, the order of the phases may be changed. That is, in someembodiments the deposition enhancing agent may be the next reactantprovided after the second reactant, while in other embodiments thedeposition enhancing agent may be the next reactant provided after thefirst metal source reactant. For example, in some embodiments the thirdphase (provision of the deposition-enhancing agent) may immediatelyfollow the first phase (provision of the reactant comprising a metalspecies), which in turn is followed by the species-contributing phase. Aphase is generally considered to immediately follow another phase ifonly a purge or other reactant removal step intervenes.

In one embodiment, an ALD cycle comprises:

1. providing a metal halide to the reaction space;

2. purging and/or evacuation of excess transition metal halide andreaction byproducts;

3. providing a second reactant to the reaction space;

4. purging/and or evacuation of excess second reactant and reactionbyproducts; and

5. providing a deposition-enhancing agent to the reaction space.

Step 5 can be included in each ALD cycle, or steps 1-4 can be repeatedseveral times before step 5 is introduced. In some embodiments steps 1-4are repeated up to 10 times before step 5 is included. In otherembodiments steps 1-4 are repeated up to 100 or even 1000 or more timesbefore step 5 is included.

With reference to FIG. 1, in an embodiment of the invention, afterinitial surface termination, if necessary, a first reactant or sourcechemical pulse is supplied 102 to the substrate or workpiece. Inaccordance with a preferred embodiment, the first reactant pulsecomprises a carrier gas flow and a volatile halide species that isreactive with the workpiece surfaces of interest and further comprises aspecies that is to form part of the deposited layer. Accordingly, ahalogen-containing species adsorbs upon the workpiece surfaces. In theillustrated embodiment, the first reactant is a metal halide, and thethin film being formed comprises a metallic material, preferably metalnitride, metal carbide, a metal silicon compound or metal oxide. Thefirst reactant pulse self-saturates the workpiece surfaces such that anyexcess constituents of the first reactant pulse do not further reactwith the monolayer formed by this process. Self-saturation results dueto halide tails terminating the monolayer, protecting the layer fromfurther reaction.

The first reactant is then removed 104 from the reaction space.Preferably, step 104 merely entails stopping the flow of the firstreactant or chemistry while continuing to flow a carrier gas for asufficient time to diffuse or purge excess reactants and reactantby-products from the reaction space, preferably with greater than abouttwo reaction chamber volumes of the purge gas, more preferably withgreater than about three chamber volumes. Preferably the removal 104comprises continuing to flow purge gas for between about 0.1 seconds and20 seconds after stopping the flow of the first reactant pulse.Inter-pulse purging is described in co-pending U.S. patent applicationhaving Ser. No. 09/392,371, filed Sep. 8, 1999 and entitled IMPROVEDAPPARATUS AND METHOD FOR GROWTH OF A THIN FILM, the disclosure of whichis incorporated herein by reference. In other arrangements, the chambermay be pumped down between alternating chemistries. See, for example,PCT publication number WO 96/17107, published Jun. 6, 1996, entitledMETHOD AND APPARATUS FOR GROWING THIN FILMS, the disclosure of which isincorporated herein by reference. Together, the adsorption 102 andreactant removal 104 represent a first phase 105 in an ALD cycle. Thefirst phase in the illustrated ALD cycle is thus the metal phase.

With continued reference to FIG. 1, a second reactant or source chemicalpulse is then supplied 106 to the workpiece. The second chemistrydesirably reacts with or adsorbs upon the monolayer left by the firstreactant. In the illustrated embodiment, this second reactant pulse 106comprises supplying a carrier gas with the second source gas to theworkpiece. In particular, where the first reactant comprises a metalhalide, the second reactant leaves no more than about a monolayer of ametal-containing species. The second reactant preferably removes atleast some halide ligands from the adsorbed first reactant. The secondreactant pulse 106 also leaves a surface termination that operates tolimit the deposition in a saturative reaction phase.

After a time period sufficient to completely saturate and react themonolayer with the second reactant pulse 106, any excess second reactantis removed 108 from the workpiece. As with the removal 104 of the firstreactant, this step 108 preferably comprises stopping the flow of thesecond chemistry and continuing to flow carrier gas for a time periodsufficient for excess reactants and volatile reaction by-products fromthe second reactant pulse to diffuse out of and be purged from thereaction space. Together, the second reactant pulse 106 and removal 108represent a second phase 109 in the illustrated process, and can also beconsidered a non-metal species-contributing phase. The second phase 109can also be considered a non-halide species-contributing phase.

When the excess reactants of the second reactant pulse have been removed108 from the chamber, a third reactant or source chemical pulse ispreferably supplied to the workpiece 110. Preferably the third reactantis a deposition-enhancing agent that is capable of removing halides fromthe substrate surface and/or the reaction space, such as hydrocarbons,hydrogen, hydrogen plasma, hydrogen radicals, silanes, germaniumcompounds, nitrogen compounds, boron compounds and boranes. Thedeposition-enhancing agent is preferably provided with an inert carriergas. Temperature and pressure conditions are preferably arranged toavoid diffusion of the deposition-enhancing agent through the monolayerto underlying materials.

After a time period sufficient to completely saturate and react themonolayer with the third reactant, excess unreacted deposition-enhancingagent and any reaction by-products (preferably also volatile) areremoved 112 from the reaction space, preferably by a purge gas pulse.The removal can be as described for step 104. Together, thedeposition-enhancing agent pulse 110 and removal 112 represent a thirdphase 113 of the illustrated ALD process, which can also be referred toas the deposition-enhancing phase.

In an alternative embodiment of the invention (not shown), supply ofdeposition-enhancing agent immediately follows the step of removingexcess first reactant and by-products. After a time period sufficient tocompletely saturate and react the monolayer with thedeposition-enhancing agent, excess unreacted deposition-enhancing agentand reaction by-products are removed from the reaction space, preferablyby a purge gas pulse. The removal step is followed by supply of thesecond reactant pulse.

In another alternative embodiment of the invention (not shown), thesteps of supplying the deposition-enhancing agent and removing anyexcess deposition-enhancing agent and by-products precede the step ofsupplying the first reactant. In other alternative embodiments, thedeposition-enhancing agent is not provided in every cycle.

The foregoing embodiments will be discussed in the context of specificthin film chemistries.

Deposition of Carbon-Containing Films

Carbon containing metal films or metal carbides have varyingapplications, such as gate electrodes, electrodes in capacitors andbarrier layers in damascene and dual damascene structures.

In one embodiment, a general pulsing sequence for carbon-containingmetal or metal carbide thin film deposition is:

(M¹X_(y)+purge+M²R₃+purge+deposition-enhancing agent+purge)×m ₁

or

(M¹X_(y)+purge+deposition-enhancing agent+purge+M²R₃+purge)×m ₁,

wherein m₁ is the number of total cycles. M¹ is a metal atom, preferablyselected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W.However, in other embodiments M¹ is selected from the group consistingof Fe, Mn, Ni, Co, Cu, Zn, Cd, Ge, Si, Sn, Sb, Ga, Ru, Ir, Pd, Pt, Au,Rh, Re, B, In and Al.

M² is a metal atom, preferably selected from the group consisting of B,Al, In, Sn, Bi, Sn, Zn, Pb, Sb and Ga. R is a ligand for M² and can beany ligand, preferably a metalorganic ligand, more preferably anorganometallic ligand, most preferably an alkane ligand, such as ethylligand.

X_(y) is one or more ligands for M¹. Each X is preferably a halogenligand selected from the group consisting of I, Br, Cl and F. However,in some embodiments at least one X can be a metalorganic ligand, such asa cyclopentadienyl (for example, cyclopentadienyl,methylcyclopentadienyl, pentamethylcyclopentadienyl,ethylcyclopentadienyl, isopropylcyclopentadienyl,tertbutylcyclopentadienyl, and indenyl), alkoxide (for example,methoxide, ethoxide, isopropoxide, and tertbutoxide), alkyl (forexample, methyl, ethyl, propyl, and butyl), carbonyl, cyclo-octadiene,benzene or hydrogen ligand. In other embodiments X_(y) may comprisemixtures thereof. However, at least one of the X_(y) ligands ispreferably a halogen. As an example, bis(cyclopentadienyl)hafniumdichloride or bis(cyclopentadienyl)tantalum(V) trichloride, can be usedas a metal precursor in some embodiments.

The deposition enhancing agent is preferably selected from the groupconsisting of hydrocarbons, hydrogen, hydrogen plasma, hydrogenradicals, silanes, germanium compounds, nitrogen compounds, boroncompounds and boranes. In a more preferred embodiment, thedeposition-enhancing agent is a hydrocarbon selected from the groupconsisting of alkanes, alkenes and alkynes.

In preferred embodiments, M² is a metals, preferably aluminum, and R isa carbon-containing ligand. M²R₃ preferably has at least onemetal-to-carbon bond. In some embodiments, M²R₃ may be considered acarbon source chemical.

One benefit of the present invention is that the growth rate isextremely high for an ALD process. For example, the growth rate for TaCformation can be over 2 Å/cycle. Further, annealing can be performedafter the metal carbide deposition for enhancing the properties of thefilm. Suitable atmospheres, such as N₂ or forming gas (N₂/H₂), may beused during annealing.

Exemplary pulsing sequences for TaC film formation include:

(TaCl₅+purge+trimethylaluminum (TMA) or triethylaluminum(TEA)+purge+C₂H₂+purge)]×m ₂

or

(TaCl₅+purge+C₂H₂+purge+TMA or TEA+purge)]×m ₂,

wherein m₂ is the number of total cycles and C₂H₂ is thedeposition-enhancing agent.

To improve film properties, acetylene (C₂H₂) was introduced in the TaCformation process as a deposition-enhancing agent as described above.Films deposited using acetylene contained about 40 times less chlorinethan films deposited without the use of acetylene. This minor amount ofchlorine is acceptable for device structures.

In another embodiment, tungsten carbide films are deposited. Anexemplary pulsing sequence may be:

(TEB+purge+Si₂H₆+purge+WF₆+purge)]×m ₂,

wherein m₂ is the number of total cycles, WF6 corresponds to M¹X_(y),TEB is M²R₃ and Si₂H₆ is the deposition enhancing agent.

A tungsten-carbide (WC_(x)) film could be produced in the prior art fromalternating and sequential pulses of WF₆ and TEB. Sequential andalternating pulses of WF₆ and TEB at about 300° C. produce lowresistivity WC_(x) films with hydrogen and fluorine impurities. Byutilizing a deposition enhancing agent in the ALD cycle described above,alternating and sequential pulses of TEB, a deposition-enhancing agent(e.g., Si₂H₆) and WF₆ at a temperature between about 200° C. and 350° C.produced WC_(x) films with no impurities (FIG. 3) and substantiallylower resistivity.

In other embodiments, a deposition-enhancing agent is not utilized everycycle but only in some of the cycles. In this situation, a generalpulsing sequence for carbon-containing metal thin film deposition canbe:

[n ₃×(M¹X_(y)+purge+M²R₃+purge)+m ₃×(enhanced deposition agent+purge)]×k₃,

wherein n₃ is the number of carbide cycles in one total cycle, m₃ is thenumber of cycles in which a deposition enhancing agent is used in onetotal cycle, and k₃ is the number of total cycles. M¹ is a metal atompreferably selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta,Cr, Mo, W, Si and Al. In other embodiments M¹ can be selected from thegroup consisting of Fe, Mn, Ni, Co, Cu, Zn, Cd, Ge, Si, Sn, Sb, Ga, Ru,Ir, Pd, Pt, Au, Rh, Re, B, In. M² is a metal atom, preferably selectedfrom the group consisting of B, Al, In, Sn, Bi, Zn, Pb, Sb and Ga. R isa ligand for M² and can be any ligand.

X_(y) is one or more ligands for M¹. Each X is preferably a halogenligand selected from the group consisting of I, Br, Cl and F. However,in some embodiments at least one X can be a metalorganic ligand, such asa cyclopentadienyl (for example, cyclopentadienyl,methylcyclopentadienyl, pentamethylcyclopentadienyl,ethylcyclopentadienyl, isopropylcyclopentadienyl,tertbutylcyclopentadienyl, and indenyl), alkoxide (for example,methoxide, ethoxide, isopropoxide, and tertbutoxide), alkyl (forexample, methyl, ethyl, propyl, and butyl), carbonyl, cyclo-octadiene,benzene or hydrogen ligand. In other embodiments X_(y) may comprisemixtures thereof. However, at least one of the X_(y) ligands ispreferably a halogen. As an example, bis(cyclopentadienyl)hafniumdichloride or bis(cyclopentadienyl)tantalum(V) trichloride, can be usedas a metal precursor in some embodiments.

A carbide film is deposited by an ALD process comprising the followingsteps:

1. providing a transition metal halide (e.g. TaCl₅, TaF₅, TiCl₄ orZrCl₄) to the reaction space;

2. removing excess transition metal halide from the reaction space bypurging and/or evacuation;

3. providing an organometallic or metalorganic compound to the reactionspace;

4. removing excess organometallic or metalorganic compound by purgingand/or evacuation; and

5. providing hydrogen radicals to the reaction space.

In some embodiments step 5 is included in each cycle, while in otherembodiments steps 1-4 are repeated multiple cycles before introducingstep 5. That is, the hydrogen radicals may be provided at intervals inthe deposition cycle. Preferably the hydrogen radicals are initiallyprovided at a point in the deposition process where the thin film isthick enough that the radicals can not penetrate the film and damage theunderlying substrate.

Deposition of Silicon-Containing Films

Silicon-containing metal films or metal silicides are commonly used asconductive electrodes. Tungsten silicide (WSi_(x)) is an example of ametal silicide. A WSi_(x) film has been formed by alternating andsequential pulses of WF₆ and Si₂H₆. However, this procedure undesirablyleads to powder generation, producing films with properties unsuited forcommon applications. It has been found that use of adeposition-enhancing agent, such as TEB, in an ALD reaction with WF₆ andSi₂H₆ can produce WSi_(x) films with improved film properties (i.e.,reduced impurity levels).

In some embodiments, silicon-containing metal or metal silicide thinfilm are deposited by the following pulsing sequence:

(MX_(y)+purge+silicon source chemical+purge+deposition-enhancingagent+purge)×m ₁, or

(MX_(y)+purge+deposition-enhancing agent+purge+silicon sourcechemical+purge)×m ₁

wherein m₁ is the number of total cycles. M is a metal atom, preferablyselected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, Wand Al. In other embodiments, M is selected from the group consisting ofFe, Mn, Ni, Co, Cu, Zn, Cd, Ge, Si, Sn, Sb, Ga, Ru, Ir, Pd, Pt, Au, Rh,Re, B, In.

X_(y) is one or more ligands for M. Each X is preferably a halogenligand selected from the group consisting of I, Br, Cl and F. However,in some embodiments at least one X can be a metalorganic ligand, such asa cyclopentadienyl (for example, cyclopentadienyl,methylcyclopentadienyl, pentamethylcyclopentadienyl,ethylcyclopentadienyl, isopropylcyclopentadienyl,tertbutylcyclopentadienyl, and indenyl), alkoxide (for example,methoxide, ethoxide, isopropoxide, and tertbutoxide), alkyl (forexample, methyl, ethyl, propyl, and butyl), carbonyl, cyclo-octadiene,benzene or hydrogen ligand. In other embodiments X_(y) may comprisemixtures thereof. However, at least one of the X_(y) ligands ispreferably a halogen. As an example, bis(cyclopentadienyl)hafniumdichloride or bis(cyclopentadienyl)tantalum(V) trichloride, can be usedas a metal precursor in some embodiments.

In preferred embodiments, the silicon source chemical is a silane(Si_(x)H_(y)). Other silicon source chemicals that can be used will beknown to the skilled artisan.

The deposition-enhancing agent is selected from the group consisting ofhydrocarbons, hydrogen, hydrogen plasma, hydrogen radicals, silanes,germanium compounds, nitrogen compounds, boron compounds and boranes. Ina more preferred embodiment, the deposition-enhancing agent is a boroncompound, more preferably triethyl boron (TEB).

In one embodiment, formation of a WSi_(x) film proceeds using thepulsing sequence:

(WF₆+purge+Si₂H₆+purge+TEB+purge)]×m ₂,

wherein m₂ is the number of total cycles and TEB is thedeposition-enhancing agent. By controlling the concentrations of thesilicon source chemical and deposition enhancing agent, highlyconductive WSi_(x) films with substantially reduced impurity contentcompared to prior art processes are produced.

Deposition of Oxygen-Containing Films

Metal oxides have several important applications, such as insulators andtransparent conductors. In future devices progressively thinner filmsare needed. In addition, they need to be grown conformally in narrowtrenches. In some applications, such as optics, nanolaminates with sharpinterfaces between materials are needed.

In one embodiment, a general pulsing sequence for oxygen-containingmetal thin film deposition may be:

(MX_(y)+purge+oxidizing reactant+purge+deposition-enhancingagent+purge)×m ₁

or

(MX_(y)+purge+deposition-enhancing agent+purge+oxidizingreactant+purge)×m ₁

wherein m₁ is the number of total cycles. M is a metal atom, preferablyselected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, Wand Al. In other embodiments, M can be selected from the groupconsisting of Fe, Mn, Ni, Co, Cu, Zn, Cd, Ge, Si, Sn, Sb, Ga, Ru, Ir,Pd, Pt, Au, Rh, Re, B, In.

X_(y) is one or more ligands for M. Each X is preferably a halogenligand selected from the group consisting of I, Br, Cl and F. However,in some embodiments at least one X can be a metalorganic ligand, such asa cyclopentadienyl (for example, cyclopentadienyl,methylcyclopentadienyl, pentamethylcyclopentadienyl,ethylcyclopentadienyl, isopropylcyclopentadienyl,tertbutylcyclopentadienyl, and indenyl), alkoxide (for example,methoxide, ethoxide, isopropoxide, and tertbutoxide), alkyl (forexample, methyl, ethyl, propyl, and butyl), carbonyl, cyclo-octadiene,benzene or hydrogen ligand. In other embodiments X_(y) may comprisemixtures thereof. However, at least one of the X_(y) ligands ispreferably a halogen. As an example, bis(cyclopentadienyl)hafniumdichloride or bis(cyclopentadienyl)tantalum(V) trichloride, can be usedas a metal precursor in some embodiments.

The oxidizing reactant or oxygen source chemical is preferably selectedfrom the group consisting of H₂O, O₂, ozone, oxygen radicals and oxygenplasma. The deposition-enhancing agent is preferably selected from thegroup consisting of hydrocarbons, hydrogen, hydrogen plasma, hydrogenradicals, silanes, germanium compounds, nitrogen compounds, boroncompounds and boranes. More preferably, the deposition enhancing agentis selected from the group including, but not limited to hydrocarbons,such as alkanes, alkenes and alkynes. In some embodiments, thedeposition-enhancing agent is acetylene (C₂H₂).

As an example, when WCl₆ is used in a deposition reaction with H₂O, thestarting surface is chlorinated, causing poor film growth andproperties. However, if a deposition enhancing agent, such as, forexample, acetylene (C₂H₂), is used in the reaction in the cycledescribed above, film growth and properties are substantially improved.The film growth may be written:

2-OH(s)+WCl₆(g)→—OWCl_(x)(s)+HCl(g)

—OWCl_(x)(s)+H₂O(g)→—OWOHCl_(x)(s)+HCl(g)

—OWCl_(x)(s)+C₂H₂(g)→—WO₂(s)+C₂H₂Cl₂(g)

As an alternative, the acetylene pulse may be applied before the waterpulse:

2-OH(s)+WCl₆(g)→—OWCl_(x)(s)+HCl(g)

—OWCl_(x)(s)+C₂H₂(g)→—OW(s)+HCl(g)

—OW(s)+H₂O(g)→—W(OH)₂(s)

As another example, MoO_(x) can be grown using MoCl₅, H₂O and adeposition-enhancing agent, such as, e.g., C₂H₂:

2-OH(s)+MoCl₅(g)→—OMoCl_(x)(s)+HCl(g)

—OMoCl_(x)(s)+H₂O(g)→—OMoOHCl_(x)(s)+HCl(g)

—OMoCl_(x)(s)+C₂H₂(g)→—MoO₂(s)+C₂H₂Cl₂(g)

As an alternative, the acetylene pulse may be applied before the waterpulse:

2-OH(s)+MoCl₆(g)→—OMoCl_(x)(s)+HCl(g)

—OMoCl_(x)(s)+C₂H₂(g)→—OMo(s)+HCl(g)

—OMo(s)+H₂O(g)→—Mo(OH)₂(s)

As discussed above, use of a deposition-enhancing agent foroxygen-containing film growth has beneficial consequences. For example,the growth rate of In₂O₃, which is an important conductive oxide, istypically low. However, use of a deposition-enhancing agent, such as,e.g., acetylene, allows removal of impurities at low temperatures. SnO₂is also an important conductive oxide. In particular, the combination ofIn₂O₃ and SnO₂ (i.e., ITO) is a very important conductive oxide.

As another example illustrating the beneficial consequences ofdeposition-enhancing agent usage, a TiO₂ film, which has a highpermittivity (˜80), usually has a high leakage current when deposited byprevious processes, which limits its use as a dielectric. Oxygendeficiency has been speculated as the reason for the high leakagecurrent. Carbon from acetylene used as a deposition-enhancing agentaccording to the present methods advantageously fills these vacanciesand overcomes these problems.

As yet another example, HfO₂ is one of the key candidates as a gateoxide in MOSFET transistors. The best electrical results have beenobtained using HfCl₄ and H₂O. However, even trace amounts of chlorinecan cause device failure. Acetylene-assisted growth cleans the interfaceand its use as a deposition enhancing agent in the methods disclosedabove allows the deposition of pure HfO₂ films at low temperatures.

Deposition of Elemental Metal Films

Conformal ALD deposited elemental metal films are desirable in manysemiconductor applications, such as diffusion barriers for Cuinterconnects, metal electrodes for gate stacks andmetal-insulator-metal (MIM) structures. For example, combination of a Cudiffusion barrier and a pure metal (e.g., W) with low resistivity can beused for direct Cu plating.

ALD of W may be achieved using sequential and alternating pulses of WF₆and a reducing agent, such as Si₂H₆ or B₂H₆. The inventors have observedthat the formation of tungsten films using dilute Si₂H₆ may lead to theproduction of powders, which makes use of this pulsing scheme inindustrial practice undesirable due to the risk of particle generation.However, powder production in the deposition of metal films can besubstantially reduced using a deposition-enhancing agent.

In one embodiment, a pulsing sequence for metal thin film deposition byALD is:

(deposition-enhancing agent+purge+MX_(y)+purge+reducing agent+purge)×m₁,

or

(MX_(y)+purge deposition-enhancing agent+purge+reducing agent+purge)×m₁,

wherein m₁ is the number of total cycles. M is a metal atom, preferablyselected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, Wand Al. In other embodiments, M can be selected from the groupconsisting of Fe, Mn, Ni, Co, Cu, Zn, Cd, Ge, Si, Sn, Sb, Ga, Ru, Ir,Pd, Pt, Au, Rh, Re, B, and In.

X_(y) is one or more ligands for M. Each X is preferably a halogenligand selected from the group consisting of I, Br, Cl and F. However,in some embodiments at least one X can be a metalorganic ligand, such asa cyclopentadienyl (for example, cyclopentadienyl,methylcyclopentadienyl, pentamethylcyclopentadienyl,ethylcyclopentadienyl, isopropylcyclopentadienyl,tertbutylcyclopentadienyl, and indenyl), alkoxide (for example,methoxide, ethoxide, isopropoxide, and tertbutoxide), alkyl (forexample, methyl, ethyl, propyl, and butyl), carbonyl, cyclo-octadiene,benzene or hydrogen ligand. In other embodiments X_(y) may comprisemixtures thereof. However, at least one of the X_(y) ligands ispreferably a halogen. As an example, bis(cyclopentadienyl)hafniumdichloride or bis(cyclopentadienyl)tantalum(V) trichloride, can be usedas a metal precursor in some embodiments.

The reducing agent is preferably selected from the group includingsilanes (e.g., Si₂H₆) and boranes (e.g., B₂H₆); and thedeposition-enhancing agent is selected from the group consisting ofhydrocarbons, hydrogen, hydrogen plasma, hydrogen radicals, silanes,germanium compounds, nitrogen compounds, boron compounds and boranes. Ina preferred embodiment the deposition-enhancing agent is a boroncompound, preferably TEB.

As one example, a low resistivity W film was formed at a substratetemperature between about 200° C. and 350° C. using the followingpulsing sequence:

(TEB+purge+WF₆+purge+Si₂H₆+purge)]×m ₂

wherein m₂ is the number of total cycles and TEB is thedeposition-enhancing agent. X-ray diffraction (XRD) spectra and x-rayphotoelectron spectroscopy (XPS) sputtering time profiles of lowresistivity tungsten films formed according to the pulsing sequenceabove showed that there was no powder formation.

Semiconductor Device Applications

Methods of fabricating semiconductor device structures will now bediscussed. Although described in terms of several specific contexts, oneof skill in the art will recognize that the processes described hereinare applicable to many other contexts as well.

Carbon-Containing Films as Electrodes

In some embodiments a electrode is formed by ALD of conductive metalcarbide. With reference to FIG. 3, a silicon substrate 200 isillustrated comprising a layer of high-k dielectric material 210. Thesubstrate may be treated prior to deposition of the high-k material. Forexample, in some embodiments, a thin interfacial layer (not shown) maybe deposited prior to deposition of the high-k material. In oneembodiment a thin chemical oxide or oxynitride is formed on the surface.In other embodiments a thermal oxide is grown on the substrate.

“High-k” generally refers to a dielectric material having a dielectricconstant (k) value greater than that of silicon oxide. Preferably, thehigh-k material has a dielectric constant greater than 5, morepreferably greater than about 10. Exemplary high-k materials include,without limitation, HfO₂, ZrO₂, Al₂O₃, TiO₂, Ta₂O₅, Sc₂O₃, lanthanideoxides and mixtures thereof, silicates and materials such as YSZ(yttria-stabilized zirconia), barium strontium titanate (BST), strontiumtitanate (ST), strontium bismuth tantalate (SBT) and bismuth tantalate(BT). Preferably, the high-k material is also deposited by an ALDprocess.

A layer or thin film of conductive metal carbide 220 is deposited overthe dielectric (high-k material) layer 210 by ALD, as described above,to form the illustrated structure. It will be appreciated that in theillustrated embodiment the layers are not necessarily drawn to scale.The metal carbide and underlying high-k material are patterned to forman electrode.

The metal carbide thin film 220 is preferably deposited over thedielectric layer 210 by contacting the substrate with alternating pulsesof a metal source chemical, carbon source chemical and adeposition-enhancing agent (not necessarily in this order), as describedabove. The metal source chemical is preferably a halide compound (e.g.,TaCl₅) and the carbon source chemical is preferably an organometalliccompound, such as, e.g., trimethyl aluminum (TMA).

The deposition-enhancing agent may be a hydrocarbon selected from thegroup including, but not limited to, alkanes, alkenes and alkynes. Inone embodiment, the deposition-enhancing agent is acetylene. (C₂H₂). Inother embodiments the deposition-enhancing agent comprises hydrogenradicals. Unreacted source chemicals and reaction by-products areremoved from the reaction chamber after each source chemical pulse, forexample by evacuation and/or purging with an inert gas (e.g., N₂). Insome embodiments, evacuation is achieved using a vacuum pump or aplurality of vacuum pumps. The pulsing cycle is repeated until a metalcarbide layer of the desired thickness has been formed. Preferably, themetal carbide layer has a thickness between about 5 Å and about 1000 Å.

The conductive metal carbides deposited to form the electrode in theseembodiments are preferably selected from the group consisting of Ti, Zr,Hf, V, Nb, Ta, Cr, Mo, W and Al carbides. Further non-conductive carbideSiC can also be deposited.

In some embodiments the metal carbide forms the electrode. In otherembodiments (not shown) another conductive material, such as a metal orpoly-Si, is deposited over the metal carbide. The additional conductivematerial may be deposited by ALD or by another deposition process, suchas by CVD or PVD. The deposition may be selective, or may be followed bypatterning steps. According to still another embodiment, annealing canbe performed after the metal carbide deposition. Suitable atmospheres,such as N₂ or forming gas (N₂/H₂) are apparent to skilled artisan.

Further processing steps, such as spacer deposition and source/drainimplantation, will be apparent to the skilled artisan.

Carbon-Containing Films as Barrier Layers

Metal carbide thin film can be deposited by ALD to form a barrier layerfor interconnect metallization. The substrate may comprise damascene ordual damascene structures, including high aspect ratio trenches andvias. With reference to FIG. 4, in one embodiment, a dual damascenestructure 300 comprises a trench 310, via 320, and dielectric layers 340and 350. In the illustrated embodiment, the layers are not necessarilydrawn to scale. The structure 300 is placed in an ALD reaction chamberand a metal carbide thin film barrier layer 360 is deposited over thetrench 310 and via 320 by contacting the structure 300 with alternatingpulses of a metal source chemical, carbon source chemical anddeposition-enhancing agent (not necessarily in this order), as describedabove.

In the preferred embodiment, the metal source chemical is a halidecompound, the carbon source is an organometallic compound and thedeposition-enhancing agent is a hydrocarbon or hydrogen radicals.Unreacted source chemicals and reaction by-products are removed from thereaction chamber after each pulse of source chemical, as describedabove. The pulsing cycle is repeated until a barrier layer of thedesired thickness has been formed. Preferably, the barrier layer has athickness between about 5 Å and about 100 Å.

In all of the aforesaid embodiments, any element used in an embodimentcan interchangeably be used in another embodiment unless such areplacement is not feasible.

It will be understood by those of skill in the art that numerous andvarious modifications can be made without departing from the spirit ofthe present invention. Therefore, it should be clearly understood thatthe forms of the present invention are illustrative only and are notintended to limit the scope of the present invention. All modificationsand changes are intended to fall within the scope of the invention, asdefined by the appended claims.

1. (canceled)
 2. A process for forming an electrode comprising:depositing a high-k layer on a substrate by atomic layer deposition(ALD); and subsequently depositing a carbon-containing metal film on thesubstrate by ALD to form an electrode structure comprising acarbon-containing metal film over a high-k layer, wherein thecarbon-containing metal film is deposited by a plurality of ALD cyclescomprising contacting the substrate with alternating and sequentialpulses of a first reactant that comprises the metal of thecarbon-containing metal thin film and a second reactant comprisingaluminum and carbon.
 3. The process of claim 2, additionally comprisingdepositing a conductive material over the carbon-containing metal thinfilm.
 4. The process of claim 3, wherein the conductive materialcomprises metal or poly-Si.
 5. The process of claim 4, wherein theconductive material is deposited by ALD.
 6. The process of claim 2,wherein the deposition of the carbon-containing metal film is selective.7. The process of claim 2, wherein the first reactant comprises a metalselected from the group consisting of Ti and Nb.
 8. The process of claim2, wherein the first reactant comprises at least one halide ligand. 9.The process of claim 8, wherein the first reactant is selected from thegroup consisting of TiCl₄ and NbCl₅.
 10. The process of claim 2, whereinthe second reactant comprises at least one organic ligand.
 11. Theprocess of claim 10, wherein the second reactant comprisestrimethylaluminum (TMA) or triethylaluminum (TEA).
 12. The process ofclaim 2, wherein at least one of the plurality of ALD cyclesadditionally comprises contacting the substrate with a third reactantcomprising a silane or borane.
 13. The process of claim 12, wherein thethird reactant comprises disilane.
 14. The process of claim 12, whereinthe third reactant comprises triethylboron (TEB).
 15. The process ofclaim 12, wherein the third reactant is provided in each of theplurality of deposition cycles.
 16. The process of claim 12, wherein thethird reactant is provided is not provided in each of the plurality ofdeposition cycles.
 17. The process of claim 12, wherein the at least oneof the plurality of deposition cycles comprises: contacting thesubstrate with a Ti or Nb halide; removing excess Ti or Nb halide fromthe reaction space; contacting the substrate with an organometallic ormetalorganic Al compound; removing excess organometallic or metalorganicAl compound from the reaction space; and contacting the substrate with asilane or borane compound.
 18. The process of claim 2, wherein the firstreactant comprises Ti, the second reactant comprises TMA or TEA and thethird reactant comprises a silane.
 19. The process of claim 2, whereinthe first reactant is TiCl₄, the second reactant is TEA and the thirdreactant is a silane.
 20. The process of claim 2, additionallycomprising annealing the carbon-containing metal film after deposition.21. The process of claim 2, additionally comprising patterning theelectrode structure.